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"Nitrogen Properties."
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Effect of 3D Printer Type and Use of Protection Gas during Post-Curing on Some Physical Properties of Soft Occlusal Splint Material
Despite the fact that three-dimensional (3D) printing is frequently used in the manufacturing of occlusal splints, the effects of the 3D printer type and post-curing methods are still unclear. The aim of this study was to investigate the effect of the printer type (digital light processing: DLP; and liquid crystal display: LCD) as well as the post-curing method with two different atmospheric conditions (air and nitrogen gas (N2)) on the mechanical and surface properties of 3D-printed soft-type occlusal splint material. The evaluated properties were flexural strength, flexural modulus, Vickers hardness (VHN), fracture toughness, degree of double bond conversion (DC%), water sorption, water solubility, and 3D microlayer structure. The printer type significantly affected all the evaluated properties. Flexural strength, flexural modulus, and fracture toughness were significantly higher when specimens were printed by a DLP printer, while VHN and DC% were significantly higher, and a smoother surface was noticeably obtained when printed by an LCD printer. The post-curing at an N2 atmosphere significantly enhanced all of the evaluated properties except water sorption, 3D microlayer structure, and fracture toughness. The current results suggested that the printer type and the post-curing methods would have an impact on the mechanical and surface properties of the evaluated material.
Journal Article
Management and Usage of Nitrogen Systems on Liquefied Natural Gas (LNG) Carriers
The importance of liquefied natural gas (LNG) vessels and the technology that enables their operations is steadily growing. Hence, in addition to professional interest, the general public also displays a considerably large interest in this issue. Today LNG carriers belong to the category of the most technologically developed vessels and therefore managing these vessels requires not only the general knowledge but also the specific knowledge relating to their cargo handling systems. To ensure the safe and economical transport of LNG by sea and to minimize the risk of fire or explosion it is necessary to understand the properties of LNG and nitrogen, an inert gas used in all phases of the carriage and transfer of liquefied gas. The subject of this research is the overall process of nitrogen management in daily operations on board LNG carriers. The aim of the research is to explain, evaluate and define the various applications of nitrogen systems on LNG carriers.
Journal Article
Influence of Evaporation Drying on the Porous Properties of Carbon/Carbon Composite Xerogels
Carbon/carbon (C/C) composite xerogels dried by evaporation were prepared in this study to observe the change of their porous properties and their morphology by nitrogen sorption apparatus and a scanning electron microscope. Resorcinol and formaldehyde (RF) sols as a matrix phase and cotton fibers (CF) as a dispersed phase were mixed and gelated to be CF/RF composite hydrogels. The composite hydrogels were exchanged by t-butanol (TBA), dried by evaporation at 50 °C, and carbonized at 1000 °C to become the C/C composite xerogels. The results show that the CF addition does not decrease the mesoporous properties of the C/C composite xerogels. Moreover, the CF addition can alleviate the pore shrinkage, and it can maintain the mesopore structure. The mesopore size and the micropore size of C/C composites are insignificantly changed because the CF addition and the solvent exchange using TBA may suppress the pore shrinkage despite the gas-liquid interface existing during the evaporation drying.
Journal Article
Injectable reactive oxygen and nitrogen species-controlling hydrogels for tissue regeneration: current status and future perspectives
Abstract
The dual role of reactive oxygen and nitrogen species (RONS) in physiological and pathological processes in biological systems has been widely reported. It has been recently suggested that the regulation of RONS levels under physiological and pathological conditions is a potential therapy to promote health and treat diseases, respectively. Injectable hydrogels have been emerging as promising biomaterials for RONS-related biomedical applications owing to their excellent biocompatibility, three-dimensional and extracellular matrix-mimicking structures, tunable properties and easy functionalization. These hydrogels have been developed as advanced injectable platforms for locally generating or scavenging RONS, depending on the specific conditions of the target disease. In this review article, the design principles and mechanism by which RONS are generated/scavenged from hydrogels are outlined alongside a discussion of their in vitro and in vivo evaluations. Additionally, we highlight the advantages and recent developments of these injectable RONS-controlling hydrogels for regenerative medicines and tissue engineering applications.
Graphical Abstract
Journal Article
Effect of Nitrogen Gas Post-Curing and Printer Type on the Mechanical Properties of 3D-Printed Hard Occlusal Splint Material
Although three-dimensional (3D) printing is clinically convenient to fabricate occlusal splints, it is still unclear how the post-curing method and the printer type can affect 3D-printed splints. This study aimed to evaluate the effect of stroboscopic post-curing at a nitrogen gas (N2) atmosphere versus post-curing in an air atmosphere, as well as the printer type (liquid crystal display (LCD) and digital light processing (DLP)) on the mechanical properties of a 3D-printed hard-type occlusal splint material. Flexural strength, flexural modulus, Vickers hardness number (VHN), fracture toughness, degree of double bond conversion (DC), 3D microlayer structure, water sorption, and water solubility were evaluated. The post-curing method significantly affected all evaluated properties except fracture toughness and 3D microlayer structure, while the printer type significantly affected all evaluated properties except flexural strength and flexural modulus. VHN and DC were significantly higher, and the smoother surface was noticeably obtained when printed by LCD printer and post-cured at an N2 atmosphere. The current results suggested that the post-curing method and the printer type would play a role in the mechanical properties of the evaluated material and that the combination of post-curing at an N2 atmosphere and LCD printer could enhance its mechanical properties and surface smoothness.
Journal Article
The influence of microbiological fertilisers on the productivity and quality of winter wheat
The study was aimed at assessing the yield and quality of winter wheat grains inoculated with Beijerinckia fluminensis (Azotovit) and Paenibacillus mucilaginosus (Phosphatovit) in a three-year experiment on leached Chernozem in the forest-steppe zone of the Middle Volga region. The seeds of the plants were treated before sowing with microbiological fertilisers, both individually and together at a dose of 2 L/t. Bacteria Beijerinckia fluminensis and Paenibacillus mucilaginosus contained in fertilisers increased the resistance of plants to adverse conditions: seedling completeness increased by 5.4%, winter hardiness by 17.4%, and harvestability by 15.0%. The use of fertilisers led to an increase in the productivity of winter wheat grain to 32.4%. The technological parameters characterising the baking properties were improved: the content of crude gluten in the grain of winter wheat has increased to 29.1% at 75 GDI (gluten deformation index) units (I group (good) of gluten quality).
Journal Article
Effects of municipal waste compost and nitrogen fertilizer on growth and mineral composition of tomato
Purpose
Since simultaneous use of organic and mineral fertilizers on the basis of their chemical compositions can lead to better plant growth and soil fertility, the roles of municipal waste compost (MWC) and nitrogen (N) fertilizer on growth and mineral composition of tomato and some soil properties were evaluated under greenhouse condition.
Methods
Treatments involved four MWC rates (0, 1, 2, and 4% on the basis of soil dry weight) and four N levels (0, 50, 100, and 200 mg kg
−1
soil). Red cloud variety of tomato was sown in treated soils and 9 weeks later dried plant shoots and soil sub-samples were subjected to analysis.
Results
Combined use of MWC and N led to better growth of tomato than sole application of either MWC or N fertilizer. Plant concentration and/or uptake of nitrogen, phosphorus, zinc, copper, iron, and manganese were increased by both MWC and N. The beneficial effect of MWC on nutrients uptake was more pronounced with N addition. Plant and soil concentrations of cadmium and lead were under the detection limit of atomic absorption spectrophotometer. Soluble salts, organic matter, sodium, chloride and DTPA-extractable zinc, copper, iron, and manganese in the soil were effectively increased with addition of MWC.
Conclusions
Due to high soil pH and calcium carbonate equivalent (CCE) values of the calcareous soil, MWC heavy metals had no hazardous effect on tomato and even played a nutritional role. The most important problem raised from MWC application was the accumulation of soluble salts in the soil which must be monitored when making repeated application of MWC over an extended period of time.
Journal Article
Effect of Different Cultivation Practices on Soil Physical and Chemical Properties for Greenhouse Vegetables under Long-Term Continuous Cropping
Five kinds of greenhouse vegetables (eggplant, loofah, tomato, cucumber and pepper) were selected in summer uprooting stage from greenhouse in Shouguang area, Shandong Province. Total nitrogen, ammonium nitrogen, nitrate nitrogen, available phosphorus, available potassium, organic matter content and pH, EC value of three soil layers were measured, respectively. The results showed that the total nitrogen, ammonium nitrogen, nitrate nitrogen, available phosphorus and available potassium in the soil were mainly accumulated in the upper soil, which made the soil acidification trend, because different farmers adopted different cultivation practices for different greenhouse vegetables in Shouguang region, but there was no significant effect on soil EC value. The input of ammonium nitrogen and nitrate nitrogen and other related fertilizers to greenhouse cucumber was higher than that of other greenhouse vegetables, but the amount of available potassium fertilizer and organic matter input to greenhouse tomato under different cultivation practices was lower than other greenhouse vegetables. In Shouguang area, the input of organic matter into greenhouse vegetables should be increased by increasing the proportion of manure input to increase the content of soil organic carbon, so as to achieve the balance of carbon and nitrogen ratio, and to provide a scientific basis for the establishment of an evaluation system for the environmental benefits brought about by chemical fertilizer reduction in greenhouse vegetables in Shouguang area.
Journal Article
Relationships between nitrogen-fixing bacteria community structure in Vicia villosa nodules, soil properties and rocky desertification degree in karst area southwest China
Rocky desertification, a common phenomenon in karst ecosystems, significantly impacts soil fertility and vegetation restoration. Therefore, understanding the relationship between nitrogen-fixing bacteria and soil properties under different degrees of rocky desertification is crucial. Our experiment was conducted to investigate the bacterial community structure and the main environmental factors affecting the distribution of the nitrogen-fixing bacteria in the nodules of V. villosa . Based on nifH gene sequence analysis, we found that the community composition of nitrogen-fixing bacteria in the nodules was significantly correlated with the degree of rocky desertification. The soil physicochemical properties affecting community composition were analyzed. The results revealed that: (1) The soil water content, alkali-hydrolyzable nitrogen content, and total nitrogen content in the slight rocky desertification area GJ4 were significantly higher than those in the moderate rocky desertification areas KY and MZ3. (2) There were significant differences in the community composition of nitrogen-fixing bacteria across the four rocky desertification areas (R 2 = 0.448, P = 0.001). Within the same area, the Shannon index in slight rocky desertification was significantly higher than that of moderate rocky desertification. Rhizobium was the dominant genus. (3) In Gejiu, Yunnan Province, it has been observed that there is a clear negative correlation was observed among rocky desertification grade, soil water content, and nitrogen-fixing bacterial diversity in the typical karst ecosystem. Specifically, intensifying rocky desertification significantly reduces soil moisture and bacterial diversity. The degree of soil rocky desertification, total nitrogen content, total phosphorus content, and pH of soil are the main factors that play a key role in the community composition of the nitrogen-fixing bacteria in the nodules of V. villosa . This study provides a theoretical basis for the control of rocky desertification.
Journal Article